Sir William II Montague, alias de Montacute, 2nd Earl of Salisbury, 4th Baron Montacute, King of Mann, KG (25 June 1328 – 3 June 1397) was an English nobleman and commander in the English army during King Edward III's French campaigns in the Hundred Years War.

During the quieter years that followed the treaty, Montacute served on the king's council. But in 1369 he returned the field, serving in John of Gaunt's expedition to northern France, and then in other raids and expeditions, and on some commissions that attempted to negotiate truces with the French. Montacute helped Richard II put down the rebellion of Wat Tyler. In 1385 he accompanied Richard on his Scottish expedition.